Datasheet

Interrupt Request (IRQ)

MC68HC711D3 Data Sheet, Rev. 2.1

Freescale Semiconductor 17

Figure 1-5. Oscillator Connections

1.9 Interrupt Request (IRQ)

The IRQ input provides a means of applying asynchronous interrupt requests to the microcontroller unit

(MCU). Either negative edge-sensitive triggering or level-sensitive triggering is program selectable by

using the IRQE bit of the OPTION register. IRQ

is always configured to level-sensitive triggering at reset.

While the programmable read-only memory (PROM) is being programmed, this pin provides the chip

enable (CE

) signal. To prevent accidental programming of the PROM during reset, an external resistor is

required on IRQ

to pull the pin to V

10 M

* Values includes all stray capacitances.

FIRST MCU

EXTAL

XTAL

4 x E

CRYSTAL

MCU

EXTAL

XTAL

4 x E

CMOS-COMPATIBLE

EXTERNAL OSCILLATOR

NC OR

10K–100K

LOAD

25 pF *

SECOND MCU

EXTAL

XTAL

NC OR

10K–100K

LOAD

10 M

MCU

EXTAL

XTAL

4 x E

CRYSTAL

25 pF *